The tool halves of injection molding machines are fastened to clamping plates or platen. One clamping plate is arranged in a rigid position and the other tool clamping plate on a machine slide. After of the tool halves are fastened to the molding machine and before the casting operation, the clamping plates are moved toward one another until the tool halves bear against each other. The molding machine closes completely by means of pressure, preferably hydraulical pressure.
A machine slide is guided by guide shoes which are attached at slide's base and run on rails located under the slide. When viewed in the running direction, two or more guide shoes may be arranged one behind the other on a rail.
When the tool halves close, deformations of the machine slide and/or of the guide rails occur. In worst case scenarios, irreparable damage to the tools halves may occur due to the high closing force.
It has been attempted to prevent such deformation using guide rails that are also attached laterally to the movable clamping plate. Such a rigid system is not readily suitable for reducing deformation forces. Further, this results in additional width of the machine, a factor which is to be avoided if possible.
DE 41 41 259 C2, equivalent to U.S. Pat. No. 5,314,327, discloses a mold closing device intended to provide precise and reliable carriage operation throughout the entire injection molding process. Therein, the movable tool clamping plate is located on the carriage such that it can be set or reset relative to the fixed tool clamping plate in all coordinates independently of the carriage with respect to the fixed tool clamping plate. The device includes a fixed tool clamping plate and a movable tool clamping plate that is movable on a carriage with two guide shoes and a flexurally rigid connecting part. Lateral guide roller that can be supported on the machine are arranged laterally on the carriage. The lateral guide rollers are adjustable via rotatable eccentric pins that are releasably fastened to the carriage.
The slide and the movable tool clamping plate, via at least three supports which are designed as bending compression members and via a vertical pivot pin displaceable transversely to the machine longitudinal axis, are connected such that they are movable relative to one another, there being an air gap between the slide and the movable tool clamping plate. The slide and the movable tool clamping plate are releasably fastened to one another by fastening screws which are arranged in the region of the marginal zones of the machine longitudinal axis and in the vicinity of the front edge and the rear edge of the movable tool clamping plate.
Publication DE 44 03 079 C1, equivalent to U.S. Pat. No. 5,547,367, discloses a mold closing device for plastic injection molding machines for accommodating large and heavy molds. Provided for the anti-friction guide is a load-compensating device which ensures reliable support in all the operating states and in which the anti-friction guide, in the static operating state, when the mold is closed, is protected from overloading by a load-limiting device. Roller recirculation shoes which are rotatable longitudinally and transversely in pendulum crosspieces are used as the anti-friction guide. The front pendulum crosspieces are mounted on the underside of the machine slide directly in sliding bearings, the rear pendulum crosspieces are mounted together with a supporting frame on an eccentric of an eccentric shaft, and both are connected via a torsion bar. The load-compensating movement is achieved via the torsion bar. The load limiting is effected by spring deflection of the pendulum crosspieces during loading and by the supporting frames and the machine slide coming down with their pressure plates on the machine frame.